1. Field of the Invention
The invention generally relates to a light-emitting device, and more particularly, to a light-emitting device with better heat-dissipating effect.
2. Description of Related Art
With the evolution of photoelectrical technology, the light-emitting mechanism of light-emitting elements is also evolved from the thermoluminescence to the electroluminescence (EL). In order to result in different light colors, the EL-based light-emitting element adopts phosphors to convert the wavelength of the light emitted from the light-emitting element and it has become a common approach.
In terms of light-emitting diode lamps (LED lamps), in order to achieve different light color, a wavelength conversion cover is normally disposed over an LED light source module. When the light emitted from the LED light source module irradiates the wavelength conversion cover, a white light conversion starts. However, both the thermal energy produced by the LED light source module and the thermal energy produced during white light conversion would be accumulated on the wavelength conversion cover to rise the temperature of the wavelength conversion cover. Since the wavelength conversion cover is made of phosphors and polymer material or glass, and the phosphors under a high temperature would produce phenomenon of thermal quenching of luminescence, the fluorescent conversion effect of the wavelength conversion cover is degraded to further produce color shift phenomenon.